Plantronics H31CD is an improved version of the original H31.  Plantronics H31CD boost the incoming audio level to make listening easier in noisy environments. Plantronics H31CD (part# 43674-01) is recommended for dispatch operators, air traffic controllers, military, stock exchange, 911 dispatch operators. The H31CD StarSet requires the Plantronics SHS1890 Adapter to connect to most Dispatch Consoles. If using it with a telephone, you need a Plantronics M22 Vista amplifier or bottom cable between the headset and the telephone. call for compatibility if you're unsure. 

Key Features:

• Receiver Impedance (ohms, at 1 kHz): 600 ± 150
• Source Drive Impedance (ohms): 600
• 1kHz sensitivity (dBPa/V, ±4 dB): 20.5
• Flexible Eartube style
• Quick Disconnect feature
• Ideal for noisy environments, featuring a complete 6-Size eartip kit.
• Ideal for those who need a comfortable, convenient headset for noisy environments.
• The ultra-lightweight, StarSet headset rests comfortably behind the ear.
• Innovative design
• All day comfort
• Easy on, easy off

Old Poly part # 43674-01

New HP part # 8K780AA#AC3